diff --git a/src/mesh/autoMesh/autoHexMesh/meshRefinement/meshRefinement.H b/src/mesh/autoMesh/autoHexMesh/meshRefinement/meshRefinement.H
index 1f8cf3f042..499c6e6c0a 100644
--- a/src/mesh/autoMesh/autoHexMesh/meshRefinement/meshRefinement.H
+++ b/src/mesh/autoMesh/autoHexMesh/meshRefinement/meshRefinement.H
@@ -859,6 +859,8 @@ public:
 
             // Merging coplanar faces and edges
 
+                //- Merge coplanar faces. preserveFaces is != -1 for faces
+                //  to be preserved
                 label mergePatchFacesUndo
                 (
                     const scalar minCos,